The 'as cast' skin of silicon bronze is rather dull if the casting is done properly, metal poured warm, mold free enough from carbon. The skin is grey/black is little bit powdery with some remnants of the casting mold attached. The black layer is black copper oxide whi...

The patina is a coloured layer on the bronze. This coloured layer can be the result of the casting process, artificially made or developed in time in an environment which makes chemical actions possible.

The color of the flame coming from the melting furnace should be slightly green. The green color is emitted by the burning copper vapor which escapes from the melt bath. Every metal burns with a specific color, copper green and is the most dominant metal in the alloy....